Many different estimates of observed precipitation are used in the river forecast process. Sources include rain gauge networks (both official and volunteer) as well as radar estimates.

National Precipitation Totals

Low Bandwidth
 

Daily 24hr precipitation report (HYDORN)
Text only, forecaster QCed. Point observations from gauges. Updates daily.

Daily 24hr precipitation from CoCoRAHS volunteers
Static images, no QC. Point observations from gauges.

Full-Featured
 

Customizable gridded precipitation
Zoomable, panable map, forecaster QCed. Gridded estimates from a combination of rain gauges and radar. May be slow on mobile devices.